Radio signal receiver

ABSTRACT

A radio signal receiver is tunable to a plurality of different reception frequencies and is set up to output a signal obtained from a radio signal received at a tuned frequency to a reproducer in an operating mode (S 8 ), and to acquire information at least about the identity of a transmitter receivable at a given frequency in a standby mode (S 2 -S 7 ), and to record said information in a memory. The receiver is set up, initially when switched on, to acquire and record (S 3 ) information on a plurality of transmitters in a standby mode (S 2 -S 7 ), before switching over to the operating mode (S 8 ). The receiver may be operated together with a control unit which is coupled to at least one sensor and is set up to turn the receiver on and/or off depending on the detection result of the at least one sensor.  
                           S1   door open     S2   start-up     S3   transmitter search     S4   switched on?     S5   frequencies remaining     S6   engine on     S7   wait     S8   reproduction

[0001] The invention relates to a radio signal receiver which is tunable to a plurality of different reception frequencies and is set up to output a signal obtained from a radio signal received at a tuned frequency to a reproducer in an operating mode, and to acquire information at least about the identity of a transmitter receivable at a given frequency in a standby mode, and to store said information in a memory. The purpose of collecting this information is to be able to select automatically, from the multiple frequencies at which the same transmitter is receivable, those transmitters with the best reception, and to tune in these transmitters in the operating mode.

[0002] Car radio receivers with this capability are known by the name Autobest.

[0003] In order for the transmitter with the best reception quality of multiple selectable transmitters to be tuned in, it is advantageous for the radio receiver to have available as much information as possible about the entire reception band. In the case of conventional Autobest receivers, operation is occasionally interrupted in the operating mode for this purpose in order, in the standby mode, to examine another frequency of the reception band to determine if, and at what quality level, a transmitter is receivable at this frequency, and what its identity is. The scanning of the entire FM frequency band for this purpose takes place over a time span of several seconds. An interruption of the audio signal output of this length tends to be unpleasant for a listener. For this reason, the conventional Autobest receiver only switches over occasionally from the operating mode to the standby mode to determine if, and at what quality level, a transmitter is receivable at this frequency and what its identity is, and then record this information. It is self-evident that this approach to scanning the entire reception band takes several minutes.

[0004] To ensure that the Autobest functionality is quickly available after switching on the receiver, a known approach is to record the information collected about the frequency band and transmitters included in this band in a memory which retains its content even after the receiver is switched off so that the stored information is immediately available when the receiver is again switched on.

[0005] This solution is not completely satisfactory for a number of reasons. First, memories of this type are expensive, and for this reason the memory capacity is not provided which would be necessary to store information on all transmitters receivable in the frequency band; on the contrary, only information on the most recently heard transmitter is stored. The result is that, when the user tunes in a new transmitter shortly after switching on the receiver, there is a considerable risk that information on the alternative frequencies for this transmitter has not been stored, and this information must therefore be collected again. Since the receiver does not “know” in advance where to find alternative frequencies for a transmitter tuned in, it must scan the entire reception band to find them—with the result that transmitter optimization reacts slowly, just as if no transmitter information had been stored at all during the OFF period.

[0006] While this disadvantage may be eliminated by the generous use of nonvolatile memory capacity for the transmitter information, another disadvantage connected with this approach is not avoided. If the receiver is in fact switched off at a first location, then moved and switched on again at a second location, the stored transmitter information at the time it is switched on relates to the transmitter region at the first location, which may be completely different from that at the second location. In this case, the complete set of transmitter information must again be collected after the receiver is switched on before reception optimization is possible.

[0007] The goal of the invention is to provide a radio signal receiver of the type referred to at the outset, as well as a system with this type of receiver, and a control unit for it which enables efficient optimization of reception immediately after input of the ON command for the receiver by the user, or at least with a shorter delay after this command is given.

[0008] Another advantage of the receiver and the system according to the invention is that it does not require any permanent memory.

[0009] One aspect of the solution to achieve the goal is a radio signal receiver of the type referred to at the outset which is set up so that initially when switched on, it acquires and records information on a plurality of transmitters initially in the standby mode before it switches over to the operating mode. While this means that the receiver is not able to supply an output signal to a reproducer for outputting the audio signal immediately after being switched on, nevertheless, this does not involve a reduction in listener comfort for a user of the receiver in an appropriate system—as the following will make clear.

[0010] In a preferred embodiment, the receiver has a device for receiving the ON command from the user and is set up to switch over from the standby mode to the operating mode when the ON command is received. This means that the receiver may begin to operate before the ON command is input by the user, and independently of this input. If the first action occurs in sufficient time before input of the ON command, collection of transmitter information by the receiver has already been completed before the user inputs the ON command to listen to an audio signal.

[0011] This means that when the user for example actuates a button which to him appears to be the receiver ON-OFF switch, this action does not switch the receiver on—this has already occurred earlier—but merely causes the receiver to switch over from the standby mode to the operating mode. Subsequent actuation of the same button may result in a return to the standby mode.

[0012] According to another aspect of the invention, the above-defined receiver is part of a system together with a control unit which is coupled to at least one sensor, and is set up to switch the receiver on and/or off depending on the detection result of the at least one sensor. A sensor of this type may be provided to detect any parameter indicating an increased probability that a user will attempt to input the ON command. A sensor of this type may, for example, have the function of detecting the approach of a user, such that the control unit automatically switches the receiver on when the approach of a user is detected.

[0013] A system consisting of a receiver and control unit installed in a motor vehicle may, for example, be coupled to the status of the door lock of the motor vehicle and detect the approach of a user when the door lock is unlocked. In other words, when the user unlocks the vehicle door, the control unit automatically switches the receiver on, and this receiver begins in its standby mode to scan the reception frequency band. The expectation is that the user will only input the ON command after sitting down in the vehicle, and by this time, the scan may already have been completed.

[0014] While the use of a sensor coupled to the status of the door lock is especially advantageous in that it enables detection of the user's approach at an early stage, the use of a variety of other sensor types is, however, also conceivable and comprised by the invention such as: a sensor coupled to the seatbelt buckle to detect when the seat belt has been fastened by the user, a weight sensor installed in the driver's seat to detect a person sitting down in the driver's seat, etc.

[0015] Since unlocking the door does not necessarily mean that a person will in fact sit down in the vehicle and switch on the receiver, it is useful to provide a second sensor to detect starting of the motor vehicle engine, which sensor enables the control unit to then turn off the receiver when, within a predetermined time span after detection of the person's approach, the second sensor indicates that the engine of the vehicle has not been started.

[0016] Signal sources other than the receiver such as a CD player, cassette tape recorder, or even a hands-free system for a car phone may also be connected to the above-mentioned reproducer. When the reproducer receives signals from one of these sources, it is not necessary for the receiver to remain in the operating mode. However, in order to keep the collected transmitter information up to date, the receiver is not turned off by the control unit in this case but is put in the standby mode in order to detect and record transmitter information. In this case, it is not of course necessary to scan the frequency band constantly; it is sufficient instead to repeat the scan at two intervals separated by several minutes.

[0017] The receiver and the components of the control unit system may be connected by a network such as a MOST network. When such a network starts up, an initialization may be required which may take several seconds, before which time the full transmissibility of the network may not be available, which transmissibility may be required especially for transmission of the output signal from the receiver to the reproducer. When the switching on of the receiver is coupled to that of the network, this time period may also be utilized to implement the scan of the frequency band so that the required transmitter information is available as soon as the network is completely initialized.

[0018] Additional features and advantages of the invention will emerge from the following description of embodiments with reference to the attached figures.

[0019]FIG. 1 is a block diagram of a MOST network as an example of a system including a receiver and a control unit according to the invention.

[0020]FIG. 2 is a flowchart of an operating procedure implemented by the control unit and the receiver.

[0021]FIG. 1 is a block diagram of a MOST network with a plurality of units connected through a ring circuit 1. These units include: a radio receiver 2; a control unit 3 which is also equipped with control elements and thus functions as the interface to the user; a reproducer 4 which receives an output signal from radio receiver 2 through the ring circuit and outputs it as an audio signal through a speaker 5; a first sensor coupled to a door lock 6, the sensor being in the form of a switch 7 directly connected to control unit 3; a second sensor coupled to a door lock 8, the sensor being in the form of a switch 9 communicating through the ring circuit with control unit 3; and a CD player 10.

[0022] The entire system is installed in a motor vehicle. Radio receiver 2 includes a volatile memory 11 which is provided to record transmitter information.

[0023] When the vehicle is turned off, radio receiver 2, control unit 3, and reproducer 4 are de-energized, and memory 11 contains no data.

[0024] When a user unlocks door lock 6, switch 7 closes and control unit 3 is supplied with current (step S1 in FIG. 2). The control unit then switches on radio receiver 2 by switching on its power supply (S2). The radio receiver initially goes into the standby mode of transmitter search S3 in which it first tunes to a predetermined initial frequency and checks whether a transmitter is receivable on this frequency and, if so, what the identity represented by the PI code is, and what its reception field strength is. If a transmitter is receivable, the associated parameters are recorded in memory 11. In the meantime, a check is made (S4) as to whether a user has already input a command through control unit 3 to switch on radio receiver 2. In general, this will not be the case immediately after radio receiver 2 is switched on since the user needs a few seconds after unlocking door lock 6 to sit down in the vehicle, and to input through control unit 3 an ON command to initiate the output of an output signal supplied by radio receiver 2. Radio receiver 2 thus initially proceeds to step S5 to see whether any frequencies are left in the frequency band of the radio receiver which have not yet been checked. If so, the receiver selects one of these frequencies and returns to step S3. If not, the scan of the frequency band is complete, and a complete set of transmitter information is stored in memory 11 which enables radio receiver 2 to select the optimum reception frequency for the reception frequency or transmitter predetermined by a user.

[0025] If it is determined in step S4 or during wait S7 that the user has input an ON command, the radio receiver switches to operating mode S8 in which the receiver provides an output signal to reproducer 4.

[0026] At a point in time which generally lies after the scan of the frequency band by the radio receiver, control unit 3 checks the position of ignition lock 8 as determined by second sensor 9. If this indicates that the engine has been started, or that at a minimum the ignition key is in the ignition and has been rotated one click further, radio receiver 2 remains on; otherwise, it is assumed that radio receiver 2 is no longer needed, and control unit 3 switches the receiver off by interrupting its supply of current; as a result, the data collected in memory II are also lost. This measure ensures that when the vehicle is turned off for an extended period with the door unlocked, radio receiver 2 does not continue to consume power unnecessarily and drain the vehicle battery.

[0027] When step S6 indicates that the engine has been started or that the ignition key has been turned, radio receiver 2 remains on and switches to wait state S7. If the user does not input a command to control unit 3 to switch on radio receiver 2, processing returns to step S3 after a predetermined time span of, for example, 15 minutes, and the scan of the frequency band is repeated. This approach keeps the transmitter data in memory 11 up to date when the vehicle is moving even when the user is not listening to the radio. As soon as the user gives the command to switch on radio receiver 2, radio receiver 2 switches to the so-called operating mode in which it supplies an output signal, obtained from a radio signal received at a tuned reception frequency, through ring circuit 1 to reproducer 4.

[0028] Even after radio receiver 2 has switched to the operating mode, it changes from time to time to the standby mode for short time spans in order to identify any receivable transmitters, and to measure and record the reception field strength for the specific individual reception frequencies different from the reception frequency tuned to. Since this action corresponds to the conventional operation of an Autobest receiver, a detailed description of the process is not required.

[0029] A number of modifications to the above method are possible. For example, opening the door is simply one of many events detectable in a vehicle which may initiate a scan of the frequency band and a collection of transmitter information. One conceivable approach would also be, for example, to detect the insertion or turning of the ignition key instead of the opening of the door. In this case as well, a short time span is usually still available between the detected event and the input of an ON command by a user, during which time at least part of the frequency band may be scanned.

[0030] Another conceivable approach is to carry out the above-described step S4 not during the in-progress scan of the frequency band but only after this has been completed, that is, between steps S5 and S6 in FIG. 2. This would have the following result: if the user gives the command to switch on the receiver before the receiver has completed the scan, the command is ignored, and reproducer 4 remains silent until the scan is complete.

[0031] If the user inputs a command to control unit 3 to turn off radio receiver 2, this does not cause control unit 3 to interrupt completely the supply of current to radio receiver 2 but only to return radio receiver 2 to the standby mode.

[0032] The same occurs when output unit 4 receives a signal not from radio receiver 2 but from the CD player 10, or another appropriate source not shown. 

1. Receiver (2) for radio signals which is tunable to a plurality of different reception frequencies and is set up to output a signal obtained from a radio signal received at a tuned frequency to a reproducer in an operating mode, and to acquire information at least on the identity of a transmitter receivable at a given frequency, and to record said information in a memory in a standby mode, characterized in that the receiver (2) is set up, when switched on, to detect and record (S3) information on a plurality of transmitters initially in the standby mode (S2-S7) before it switches over to the operating mode (S8).
 2. Receiver according to claim 1, characterized in that it has a device to receive an ON command from a user, and to switch from the standby mode (S2-S7) to the operating mode (S8) upon receiving the ON command.
 3. System with a receiver (2) according to claim 1 or claim 2, and a control unit (3) for the receiver, characterized in that the control unit (3) is coupled to at least one sensor (7), and is set up to turn the receiver on and/or off depending on the detection result of the least one sensor (7).
 4. System according to claim 3, characterized in that the sensor (7) is a sensor for the detecting the approach of a user, and that the control unit automatically switches the receiver on when the approach of a user is detected.
 5. System according to claim 3 or 4, characterized in that said system is installed in a motor vehicle.
 6. System according to claim 5, characterized in that the sensor (7) is coupled to the status of the door lock (6) of the motor vehicle, and detects the approach of a user as the user opens the door lock (6).
 7. System according to claim 5 or 6, characterized in that said system includes a second sensor (9) to detect the starting of the motor vehicle engine, and that the control unit (3) switches off the receiver (2) if the second sensor (9) indicates within a predetermined time span after detection of the approach that the engine of the vehicle has not been started.
 8. System according to one of claims 3 through 7, characterized in that said system includes a reproducer (4) to selectively output an output signal from the receiver (2) or an output signal from another source (10) as an acoustic signal, and that the receiver (2) remains permanently in the standby mode when the reproducer (4) receives an output signal from another source (10).
 9. System according to one of claims 3 through 8, characterized in that the control unit (3) and the receiver (2) are connected through a network (1), start-up of which requires an initialization time span, and that the switching on of the receiver is coupled to the start-up of the network. 